Cast Iron or PVC Sewer Line: What Should Homeowners Choose?

When your sewer line isn’t functioning properly, or you’re on a home project and need to install a new sewer line, the question is sure to arise: which do you prefer, cast iron sewer pipe or PVC sewer line?

It’s not a simple choice. From the kitchen to the bathroom, and from outside plumbing to the sewer line, your sewer line processes all of the water that leaves your house. If you get it wrong, you will end up paying for expensive drain repair in the future.

Well, let’s cut to the chase and tell you the truth about the situation like a professional plumber would.

What Is a Cast Iron Sewer Pipe, and Where Did It Come From?

For over 100 years Canadian homes have incorporated cast iron drain pipe into their household plumbing. If your home was constructed before 1975, you’re likely to still have some of the original cast iron plumbing under your floors and walls.

The call was genuine. Cast iron is heavy, dense and quiet. The cast iron drain pipe was used for a long time in older homes and multi-unit buildings because the water flowing through it has almost no sound.

The problem with that, though, is . . The corrosion process of cast iron is an inside out process. You won’t see it happening. When you begin to notice issues such as slow drains, sewage odor or water stains on the ceiling, the pipe may have been degrading for years.

That corrosion occurs more quickly in hard or mineralized water areas of Ontario. Hamilton, Niagara and parts of the GTA have experienced increased pipe corrosion on older cast iron plumbing systems.

What Is PVC and Why Are Plumbers Choosing It Now? 

You may be familiar with PVC (polyvinyl chloride) pipe, which has been used in renovating for the past 30 years. It’s white or grey, lightweight and goes together fast. PVC, the most popular choice, is employed in new construction sewer line installation and many drain repair projects throughout Canada for residential plumbing.

Why it’s so popular:

It doesn’t rust. Ever. PVC drain pipe is not subject to corrosion, pinhole leaks like cast iron pipes get over the years, or mineral deposits as metal pipes do.

Plus, it is much more affordable. The approximate cost of a PVC sewer pipe installed is CAD $50 – $100 per linear foot. Cast iron ranges from $150 to $250 per foot. That gap can cost thousands of dollars if you are having a complete sewer line replacement.

Since PVC is lightweight, your plumber will be able to move quicker. The fewer hours that are needed, the lower the bill will be.

Cast Iron Sewer Pipe vs PVC Sewer Line: Side by Side 

Is PVC or Cast Iron Better for Canadian Homes? 

On almost any front, PVC wins for most Canadian homeowners.

Plumbing systems are tough to deal with during winter months in Canada. The freeze-thaw cycle can cause stress on pipes, particularly for older homes where insulation is not as effective. PVC is more tolerant of temperature fluctuations and changes than aging cast iron plumbing, as well as drain repair is easier and less expensive if there are any problems.

It’s not an overly complicated reason for most families. The cost for replacing the entire sewer line with cast iron is $6,000 – $9,500 CAD. Where PVC is concerned, you will expect a lower price and a pipe system that will serve you for many years, with very little maintenance.

However, not all situations require plastic sewer pipes. In certain instances, cast iron is still practical, and a qualified plumber will let you know when.

When Does Cast Iron Still Make Sense? 

Cast iron plumbing is not “out of the question”. It still has a place in some circumstances.

The largest is noise sensitive buildings. Cast iron drain pipe is especially used in Toronto and throughout the GTA’s high-rise condos, apartment buildings and hotels due to it’s sound dampening properties. You do not want to hear all of the flushing from the unit above you.

Another area where cast iron has a foothold in commercial plumbing is its ability to resist corrosion.Another advantage of cast iron in commercial plumbing is its resistance to corrosion. Buildings, restaurants and industrial properties that are used intensively may need the strength and fire resistance of cast iron.

So what if you are already using the cast iron that is in good condition? It doesn’t have to be ripped out. If the existing pipes can be relined with cast iron pipe lining methods, which is a less intrusive and more often than not more cost effective option than pipe replacement, then the plumbing inspection will inform you of that.

Does PVC Plumbing Have Any Downsides?

Yes and they are not to be hidden away.

PVC is certainly noisier. The sound of water running in plastic sewer pipes is greater than cast iron pipes. That noise may be heard in open structure homes and completed basements.

It is also not able to endure very hot temperatures. PVC is not the optimal choice for drain lines that are located close to commercial dishwashers or some industrial equipment. In such situations, cast iron or another alternative will be the better option.

And PVC can’t be used outdoors in direct sunlight without UV protection. If the plumbing lines that you are connecting are on the outside and exposed, then you should look for an alternate material or at least a protective sleeve.

What Do Canadian Plumbing Experts Actually Recommend?

In most cases when it comes to residential plumbing services throughout Southern Ontario, here’s the professional advice:

Use PVC as much as possible. It is reliable, code approved, cost efficient to install and repair. Most GTA plumbers are using PVC today for bathroom plumbing, kitchen plumbing, basement drain lines, and main sewer lines.

Invest in or store cast iron where sound is significant or commercial grade durability is needed.

In multi-unit buildings a common practice is to use cast iron on the vertical stacks where sound is transmitted between the floors, and PVC on horizontal drain lines where the sound is not transmitted anyway.

Which Pipe Material Works Best by Property Type and Region in Southern Ontario? 

This is the question most blogs skip. But where you live and what kind of property you have matters a lot.

Toronto 

From the Annex to downtown, Toronto offers a vast array of housing options, from century old semis to new condo towers. Many of the homes built before 1980 in Toronto still have original cast iron drain pipe which is nearing or has expired its useful life.

PVC is the best choice for repipes and new sewer in residential homes. Labour savings are large; material is good in terms of soil and water in Toronto.

Hybrid is the typical strategy for condos and commercial buildings in Toronto. Cast iron on vertical, PVC on branch lines. This is the line of thought that much of the licensed plumbing Toronto gets tends to go.

Mississauga and Oakville 

Generally, water quality in Mississauga and Oakville is good, so pipe corrosion does not immediately concern them, as it does in other areas. For new construction and renovations, however, most local plumbing contractors are now going with PVC.

Pre-2000 construction of plazas and office buildings in Mississauga are likely to still use copper or cast iron pipe plumbing. Before issues arise, it is best to have a professional sewer repair evaluation.

Hamilton 

Some plumbing situations need professional eyes immediately. Don’t wait on these:

• Sewage backing up into basement drains or floor fixtures
• Persistent slow drains in multiple parts of the home
• Foul odour from drains with no obvious cause
• Visible damage to exposed cast iron plumbing
• Planning any kitchen plumbing or bathroom plumbing renovation that moves drain lines
• Older home (pre-1980) with no history of sewer inspection

For anything after hours, a 24 hour plumber or local emergency plumber can respond fast enough to prevent serious damage.

About BOS Plumbing and Drains 

BOS Plumbing and Drains is a well-known brand throughout Southern Ontario, having over two decades of experience in residential and commercial plumbing. The team serves the GTA, Mississauga, Oakville, Hamilton, Milton, Niagara and Cambridge serving a wide range of services from cast iron sewer pipe evaluations, complete sewer line installation, emergency drain repair, kitchen and bathroom plumbing upgrades and more.

From a professional camera inspection of existing cast iron drain pipe to a complete repipe to PVC or emergency plumbing in Toronto at 2 am, BOS Plumbing can help.

Services include:

• Sewer line installation and full pipe replacement (PVC and cast iron)
• Cast iron pipe lining and repair
• Emergency plumbing repair and 24 hour plumber services across the GTA
• Drain repair and drain cleaning
• Bathroom plumbing and kitchen plumbing upgrades
• Outside plumbing and hose bib installation
• Residential plumbing and commercial plumbing assessments
• Water heater installation

Looking for the best plumbers Toronto and surrounding areas? BOS Plumbing’s staff is familiar with the characteristics of the water in Southern Ontario, soil conditions, and the older housing market, both inside and out.

Final Thoughts 

PVC sewer line is a practical, economical and lasting solution for the plumbing needs of most Canadian homeowners. It is low in cost, simple to repair and resistant to Canadian winter and diverse water conditions.

Sewer pipe cast iron continues to have its use in multi-unit residential buildings, noise sensitive applications in commercial buildings, and in some special applications. Before replacing an old cast iron pipe, however, if you have original cast iron that is in good condition, a cast iron pipe lining assessment can save you a lot of money.

The secret lies in hiring an honest and qualified plumber who is familiar with your area, water quality and the condition of your building.